Why didn't Iran use its capability to take down enemy jets for an entire month?
1. Iran was retarded and didn't preemptively strike US staging who had local overmatch and first mover advantage. Nothing to do but weather hits, chip away at regional basing and wait until US+Israel operation tempo goes down. Can't sustain surge sorties forever, especially with regional logistics wrecked. US pilots tired now, on stims, making mistakes.
2. Iran not remain retarded, was hide and bide, waited for US to get complement, gathering data / building tactics to squeeze out surface-air without getting glassed. Regardless, Iranian capability seems much less degraded than claimed. Who knows how many of the 20k+ targets hit was basically just drawing down highend munition inventory, which now forces flying closer on lower end munitions.
At the end of the day, Iranian mosaic forces are chilling in underground bunkers waiting for US+co to make mistakes. Consider Iraq, a much smaller country by every metric ate 5x more sorties from more carriers and sustained regional air campaign and fell because they hedged on centralized IADs. Granted most Iranian hits are precision munitions (more efficient per sortie), but we simply should not expect Iran doctrine built on distributed survivability to be remotely defeated relative to effort expended.